is your kickpanel area clean? lots of leaves there usually , andif so will kick water in.
any leaks from under the cowl/firewall, holes not plugged up ?
You might use a hose and go over several areas see, iff you see any leakage
I "think" the kick panels area drains at the same place the top does = in the rocker panel...the conv. top gutter drains into the rocker ,then into the rocker, then behind the front wheel it drains, could that be plugged? get in under the car ,I think you can tell where that drain is (going from memory here) use a coat hanger or such and clean it out....
